Operating mechanism



Dec. 23, 1969 H. E. FlsK ET Ax.

OPERATING MECHANI SM 2 Sheets-Sheet l Filed April 25, 1968 .NGE

Y BZ

INVENTORS ds EM E .T mmf/Mm WM H n Dec. 23, 1969 H. E. FisK ET AL OPERAT ING MECHANI SM 2 Sheets-Sheet z Filed Apri; 25, 1968 .vdi

United States Patent O U.S. Cl. 200-167 10 Claims ABSTRACT F THE DISCLOSURE An operating mechanism adapted to be disposed in fixed, sealed relation through an opening in a transformer casing, for actuating protective apparatus disposed therein. The operating mechanism includes a tubular member adapted to be disposed in fixed, sealed relation through the opening in the casing, a unitary handle and hollow shaft member which has the handle disposed at one end. of the shaft, and the other end disposed through the opening in the tubular member, and a socket base disposed within the hollow shaft which has electrical contacts and spring means for engaging the contacts of a bayonet type light bulb, and for biasing the `bulb towards the handle end of the shaft. The hollow shaft includes first and second longitudinal grooves disposed 180 apart in the sur- BACKGROUND OF THE INVENTION Field of the invention The invention relates in general to operating mechanisms, and more specifically to operating mechanisms for mechanically actuating encased protective means from outside the casing.

Description of the prior art Certain types of electrical distribution transformers include mechanical protective means, such as a circuit breaker, disposed within the transformer casing. The circuit breaker is responsive to the magnitude of the electrical load current and to the oil temperature, tripping to disconnect the load from the transformer to prevent dangerous overloads and short circuits from damaging the transformer. Further, the circuit breaker may be of the type which provides an electrical signal at a predetermined overload, in advance of the overload at which lautomatic tripping of the breaker will occur. This electrical signal is used to operate an overload signal light which warns of dangerous overloads and provides continuous load monitoring to permit correction or replacement with a transformer of greater capacity, before an outage occurs.

The circuit breaker is disposed within the transformer casing, in order to be responsive to the temperature of the transformer oil, With its bimetal being disposed in the top oil. The load current also passes through the 'bimetal. Thus, the bimetal is responsive to the temperature of the oil and the temperature rise provided by the magnitude of the load current. The bimetal temperature, therefore, closely follows the temperature of the transformer windings.

Since the circuit breaker by necessity must be encased Mice within the transformer tank, some actuating or operating mechanism must be provided for manually operating the breaker from outside the casing, and the operating mechanism should contain the overload signal light such that it will be clearly visible from a distance.

In the prior art, the operating mechanism includes a machined brass tube, having the conventional longitudinal and connecting circumferential slots machined in one end for receiving the pins of a bayonet-type light bulb, a forged brass handle having an opening for receiving the slotted end of the tube, which parts are brazed together to form a combination handle and shaft for the operating mechanism, a socket base disposed within the brass tube having spring loaded electrical contacts on the end adjacent to the handle, and terminals for connecting to the circuit breaker signal light contacts on the other end, and a brass quadrant which is disposed in fixed sealed relation through an opening in the transformer casing, through which the shaft portion of the shaft-handle combination is inserted, in rotary, sealed relation therewith.

While the prior art operating mechanism is satisfactory from a functional view point, the brass forgings, the machined brass parts, and the brazing step required to join the forged handle to the machined Ibrass tube, all combine to make the prior art operating mechanism costly to manufacture. It would be desirable to be able to die cast the shaft and handle as a unitary assembly, but the longitudinal slots, along with the necessary connecting circumferential slots, for receiving and locking the bayonet-type light bulb, pose the problem of how to remove the cast from the die casting mold, as the circumferential slot forming portion of the mold Will obstruct the removal of the casting. Machining the slots in the die cast part, after the die casting operation, is not a practical solution either, as parts which are die cast may be relatively porous once the skin of the casting is broken by machining. Since the operating mechanism is disposed through the transformer casing, it must be sealed, and any air leakage through the metal itself would cause the part to be rejected upon pressure test, and if not detected upon test, would deleteriously affect the life of the transformer. This restriction against machining the end of the shaft which extends outwardly from the casing is especially important in view of the fact that the end of the shaft which is encased must be machined with external circumferential grooves in order to accommodate snap rings for holding the shaft and handle in assembled relation with the quadrant, and in order to connect an operating 'arm to the end of the shaft. Therefore, since the skin of the die cast part necessarily must be broken on the portion of the shaft within the casing, it is of the utmost importance that no machining be performed on the portion of the die cast shaft disposed outside of the casing, as this would set up a flow path through the porosity of the cast part, through the wall of the casing.

The socket base and contact assembly of the prior art contains two trombone type spring loaded sliding contacts, with the housing for the sliding contacts extending longitudinally through the socket base, where they provide terminals for the signal light leads from the circuit breaker. This assembly, while functionally acceptable, is relatively costly to manufacture. It would be desirable to eliminate the sliding spring loaded contacts without losing the urging force which the contacts are required to assert against the bulb, in order to lock the pins of the bayonet type bulb in the circumferential slots.

SUMMARY OF THE INVENTION Briefly, the present invention is a new and improved operating mechanism which performs all of the required functions of actuating an encased circuit breaker while providing a pressure4 seal, and acconnnodating,thev

ing mechanism being such that its manufacturing cost is substantially less than the cost of prior art operating mechanisms having'similar functions. w I

The' handlev land hollow shaft arelformed in one piece, with a construction which lends` itself 'to aluminum die casting. The hollwshaft has first and secondlongitudinal grooves disposed in the surface which definesrits inside diameter'Qstarting at thehandle end of the shaft and contining for a predetermined dimension. The hollow shaft also has first and second circular openings disposed through its side wall portion, with the first and second circular openings intersecting one side'of the rst and second longitudinal grooves, respectively. The openings are located relative to the grooves such that the pins of a bayonet-type light bulb may slide in the grooves as the bulb is moved axially into the handle end of the hollow shaft, and when the pins are past the intersection of the circular openings with the grooves, the bulb may be rotated and the pins moved into the circular openings. When the bulb is released, spring pressure from electrical contacts disposed within the hollow shaft force the pins into the curved portions of the circular openings which are closest to the handle end of the shaft, with the pins now being closer to the handle than the point of intersection between the circular openings and the grooves, thus locking the bulb in place. This combination handle and shaft may be die cast, as the longitudinal grooves in the -inside surface of the hollow shaft are easily formed without obstructing the removal of the die cast part from the mold, and the circular openings through the wall of the hollow shaft may be formed by retractable pins which are extended during the casting operation, and which are retracted prior to the removing of the finished part from the mold.

The socket base and contact construction is arranged to receive a bayonet type bulb having a single contact at its base end. The socket base is longitudinally stepped, with the step closest to the handle end of the hollow shaft having a Ushaped contact formed of a conductive material having spring characteristics. One leg of the U- shaped contact is fixed to the first longitudinal step, and the other leg is disposed to contact the single contact of the bulb, and to be moved by the bulb towards the fixed leg. The spring characteristics of the contact cause the contact to exert an axial force on the bulb, towards the handle end of the shaft, which locks the bulb in its assembled position.

Completing the electrical circuit from the metallic tubular base of a bayonet type bulb7 of the type having a single contact, through the aluminum die cast handleshaft combination may lead to unreliable operation. Therefore, the second longitudinal step has a contact fixed thereto which extends toward the handle end of the shaft for a distance sufiicient to contact the metallic tubular base of the bulb.

BRIEF DESCRIPTION OF THE DRAWINGS Further advantages and uses of the invention will become more apparent when considered in view of the following detailed description and drawings, in which:

"FIGURE 1 illustrates an operating mechanism constructed according to the teachings of the invention, and typical protective apparatus which may be actuated thereby, with the operating mechanism being shown in a sectional side elevational view, and the protective apparatus being shown in perspective;

FIG. 2 is an end view of the operating mechanism shown in FIG. 1, without the bulb and lens;

FIG. 3 is a side elevational view, in section, of a unitary shaft and handle assembly constructed according to another embodiment of the invention FIG. 4 is an end View ofthe shaft and handle assembly shown in FlG. 3;

. -FIQ .5. i.s ..a perspetire View ataaswsmkst.,

nEsCRrPrIoN oF REEERRE EMB oDiMENr AReferring now tothe drawings, and'FIGSjI and 2 in lparticular, there is shown side and end views, respectively, of an operating mechanism 10 constructed according tothe teachings of an embodiment of the invention. As shown in FIG. 1, operating mechanism 10 is disposed in sealed relation through an opening in the casing 12 of an ele'ctrical transformer, for mechanically actuating a circuit breaker 14 disposed Within the casing 12..

In general, operating mechanism 10 includes a substantially tubular metallic member y16, which is disposed in sealed, fixed relation through an opening in the casing 12; a unitary hollow shaft and handle member 20 including a handle 22 and a shaft 2'4, with the shaft 24 being disposed through the opening in the tubular member 16, in sealed rotary relation therewith; a socket base and contact assembly 26, disposed in sealed relation within the opening of the hollow shaft 24; an operating arm 28V fixed to the shaft 24, which is connectable to circuit breaker 14 via a mechanical linkage, such as linkage 29; a bayonet type light bulb 30, which is locked in position at the handle end of the unitary handle and shaft member 20; and, a translucent lens 32 disposed about the glass portion of the light bulb 30. The light bulb 30 and lens 32 are not shown in FIG. 2, in order to more clearly illustrate the construction of the remaining components of the operating mechanism 10.

The tubular member 16, which is referred to as a quadrant in the art, may be formed of die cast aluminum, such as aluminum alloy 360, followed by an anodizing bath to increase its corrosion resistance. It has rst and second ends 17 and 19, respectively, and it has four major outer diameters, with the first outer diameter starting at the second end 19 and being defined by a surface 34, and then stepping outwardly to a second and larger outer diameter upon which threads 36 are machined after the memberA is die cast. The threads 36 are not shown in section in FIG. 1, as the section through the quadrant has been taken4 through two of four lequally spaced longitudinal grooves in the threads, which have the function of receiving one or more projections in the opening in the casing 12, such as projection 39, for aligning and fixing the circumferential location of the quadrant 16 relative to the casing 12. The second outer diameter increases to a third outer diameter defined by a surface 38, providing a shoulder 40, and the third outer diameter increases to a fourth outer diameter defined by surface 42, which extends to the first end 17 of the quadrant 16.

Quadrant 16 has a first inner diameter starting at end 19, defined by a surface 44 which is substantially c0- extensive with the outer surface 34, and the first inner diameter increases to a second inner diameter defined by a surface 46, forming a shoulder 48, which surface is substantially coextensive with the outer surfaces 38 and 40, extending to the first end 17.

The surface 46 which defines the second inner diameter is partially cut away at the first end 17 of the quadrant, to a third inner diameter, forming first and second spaced arcuate depressions 50 and 52 in the first end 17 of the quadrant. The first end 17 of quadrant 16 has the letters R, O, L and C formed therein, reading clockwise, which are uniformly spaced adjacent the first arcuate depression 50, and the letters C, L, O and R, reading clockwise, which are spaced adjacent the second arcuate depression 52. The letters R, O, L and C indicate the position of the handle 22 for resetting the breaker, opening the breaker, resetting the signal light, and closing the breaker,

respectively. Two arcuate depressions are included in quadrant 16, with the sequence of the letters being reversed between the two, in order to make the quadrant applicable to counterclockwise rotation from the closed position to the reset position of the breaker, as illustrated in FIG. 2, or clockwise rotation from the closed position to the reset position of the breaker. A projecting portion on the handle-shaft member rides in either the arcuate depression 50, or the arcuate depression 52, as selected at the time of assembly for the specific application, limiting the handle movement within the arcuate limit se` lected.

The quadrant 16 is disposed in xed, sealed relation with casing 12, with end 19 being inserted through an opening in casing 12 sized to accept the OD of the thread 36. The quadrant is aligned relative to the casing, with one or more outwardly projecting portions in the opening of the casing maintaining the selected alignment by entering the longitudinal grooves in the threads 36. A

gasket member 54 is disposed between shoulder 40 of the i quadrant 16 and the casing 12, and a suitable nut 56 cooperates with threads 36 to hold quadrant 16 in fixed relation with the casing 12.

The unitary handle and shaft member 20 may also be die cast of a material such as aluminum alloy 360, followed by an anodizing bath to increase its corrosion resistance. The unitary handle and shaft member 20 is shown in separate side and end views, respectively, in FIGS. 3 and 4, in order to more clearly illustrate its construction. It is given the reference numeral 20 in FIGS. 3 and 4 due to a modification therein which will be hereinafter explained. Like reference numerals in FIGS. 1, 2, 3 and 4 indicate like components in the unitary handle and shaft member.

The handle portion 22 includes an opening 58 to facilitate hook stick operation, it contains a cut-out portion 60, to increase the visibility of the signal light from below when the transformer is pole mounted, it includes projecting ears 62 and 64 which enter suitably disposed openings in the lens 32 to fix the lens in its assembled location, and a projection 66 which enters the arcuate depression 50, as shown, or the arcuate depression 52, depending upon the specific application, to limit the arcuate travel of the handle and shaft combination.

The hollow shaft portion 24 is integral with handle 22, with the opening in the shaft 24 being accessible from the handle end of the assembly 20, as well as from end 68 of the shaft.

Starting at the handle end of the shaft 24, shaft 24 has a first outside diameter, defined by a surface 70, which diameter is slightly less than the inside diameter of quadrant 16 defined by surface 46. The first outside diameter is stepped inwardly to form a second outside diameter, defined by a surface 72, which is of sufficient longitudinal length to receive a gasket member 74. Gasket member 74 is telescoped over surface 72 before shaft 24 is inserted into the opening in quadrant 16, with gasket member 74 providing a rotary seal between the shaft and quadrant. A suitable lubricant may be strategically placed on the inside diameter of the quadrant and the outside diameter of the shaft, adjacent the position of the gasket member, prior to assembly, in order to facilitate assembly and subsequent rotary operation of the shaft 24 within the quadrant 16. The second outer diameter of the shaft is stepped inwardly at the end of gasket member 74, to a slightly smaller diameter defined by surface 76, which diameter is slightly less than the inside diameter of quadrant 16 defined by surface 44. The inside diameter of surface 44 of quadrant 16 is slightly less than the outside diameter which provides the gasket surface 72 on shaft 24, thus limiting the axial travel of the shaft 24 into the quadrant 16.

The surface 76 of shaft 24 is continued substantially to its end 68, where it may be tapered inwardly at 76 to facilitate the insertion of snap rings over surface 76. Surface 76 has a plurality of spaced circumferential grooves 78, 80, 82 and 84, for receiving snap rings. Groove 78 has the function of receiving a snap ring 86, which holds quadrant 16 and the handle and shaft member 20 in assembled relation. Groove may receive a snap ring after an operating arm is disposed next to snap ring 86, in the event it is desirable to place the operating arm at this location; or, the operating arm may be disposed nearer the end 68 of shaft 24, such as operating arm 28, by disposing a snap ring 88 in groove 82, telescoping operating arm 28 over the shaft next to snap ring 88, and then disposing snap ring 90 in groove 84 to retain the operating arm 28 at this operating position.

The operating arm 28 must be circumferentially positioned in a predetermined orientation relative to the position of handle 22. Thus, shaft 24 has four equally spaced longitudinal grooves which extend from the end 68 to at least radial groove 78, such as longitudinal grooves 92, 93 and 94, and operating arm 28 has four equally spaced projections which slide into these grooves. This allows the operating arm 28 to be placed in any one of four circumferential positions.

Shaft 24 has a first inside diameter starting at its handle end, defined by a surface 98 which forms the bulb socket wall, a second inside diameter which is slightly less than the first, defined by a surface 100 which is adjacent a portion of the socket base asembly 26, a third inside diameter which is slightly less than the second, defined by a surface 102, which is adjacent the remaining portion of the socket ybase assembly 26, and which continues until substantially the start of the longitudinal grooves 92, 93 and 94, at which point the inside diameter of the shaft 24 is tapered to a substantially smaller inside diameter defined by a surface 104, in order to maintain a sufficient wall thickness adjacent the relatively deep longitudinal grooves.

In the embodiment of the invention shown in FIGS. 1 and 2, the prior art type of socket base and contact assembly 26 is shown, which has a substantially cylindrical insulating base portion 106, having a first outer diameter defined by a surface 108, and a second slightly smaller outside diameter defined by a surface 110. The shoulder formed between surfaces 100 and 102 of shaft 24, mate with the shoulder formed between the surfaces 108 and 110 of base portion 106, to locate the base portion 106 axially within shaft 24.

Socket base and contact assembly 26 has two similar contact structures 110 and 112, with contact structure 110 including a metallic member 114 which extends in sealed relation longitudinally through the socket base portion 106. The end of member 114 which faces end 68 of shaft 24 has a blind opening therein for receiving electrical lead 116, which is fixed in the opening by crimping the end of member 114 as shown at 118. The end of metallic member 114 which faces the handle end of shaft 24 has a spring loaded contact 120, which is axially slidable within member 104 against the pressure of a suitable spring disposed therein.

Contact structure 112 is of similar construction, and it is connected to an electrical lead 122. Electrical leads 116 and 122 are connected to be responsive to the overload contacts in circuit breaker 14, as illustrated generally by dotted line 124, An electrical potential is developed between electrical leads 116 and 122, and thus between the slidable contacts of the contact structures 110 and 112 when the overload signal contacts close in circuit breaker 14.

Since socket base and contact assembly 26 must be sealed within the opening in shaft 24, a suitable adhesive or sealing compound 123 may be disposed about the end of assembly 26 which faces the end 68 of shaft 24.

The structural arrangement of shaft 24 for receiving and locking the bayonet-type light bulb 30, includes first and second longitudinal grooves and 132, disposed apart on the inner diameter surface 98, starting at the handle ,endiof the shaft andcontinuing toward endA 68 of shaft 24 for a length sufiicient to accommodate the pins, such as pin 96 shown on light bulb 30. The inner diameter of shaft 24, defined by surface 98, is sufficient to accept the tubular metallic base of light bulb 30, but not the pins. The longitudinal grooves 130 and 1,32 are of sufficient depth to allow the pins of the bulb 30 to be disposed therein, and to allow the bulb 30 to be moved axially into the handle end of the shaft. In addition to the grooves 130 and 132, the wall portion of shaft 24 defined by inner surface 98 and outer surface 70, has first and second openings or holes 134 and 136 disposed therein, 180 apart. Openings 134 and 136 are preferably circular in configuration, for purposes which will be hereinafter explained.

The axial or longitudinal location of the openings 134 and 136 is chosen such that the contacts on bulb 30 will slightly depress the spring loaded contacts 110 and 112 when the pins of the bulb are pressed by the spring force against the side of the openings nearest the handle end of the shaft 24. The circumferential location of openings 134 and 136 is chosen such that the openings 134 and 136 intersect one side of longitudinal grooves 130 and 132, respectively, as best shown in FIGS. 2, 3 and 4. These openings should intersect its associated groove such that the pins of the bulb 30 may be turned into the openings, once they are moved axially past the point of intersection between the openings and the grooves. The geometric center of an opening should not be any closer to the center line of its associated groove than necessary to intersect the groove, as it is critical that the surface which defines the opening, nearest the handle end of the shaft 24, must be closer to the handle end than the point of intersection between the openings and the grooves. Thus, when the bulb 30 is twisted to turn its pins into the openings, the spring force of the contacts 110 and 112 will push the pins into the curvature of the openings closest to the handle end of the shaft, requiring an axial force on the bulb directed towards end 68 of the shaft, followed by turning the bulb, to unlock and remove the bulb.

This arrangement of grooves and openings is very important, as it allows the handle and shaft 24 to be integrally die cast, without encountering problems in the removal of the cast part from the dies. The male mold of the die is constructed to provide the longitudinal grooves 130 and 132. When the male and female portions of the die are in assembled relation, retractable pins in the female portion of the die are extended, the dies are heated to prevent premature freezing, and the molten aluminum is injected into the die cavity. After the aluminum has solidified, the 4retractable pins are retracted, and the cast part may be removed from the dies.

As hereinbefore stated, it is preferable that the openings 134 and 136 be circular, but it is to be understood that the important criterion is that the opening have a curvature therein facing the handle end of the shaft 24. Therefore, the die pins which form the openings in the die cast part may be semicircular in shape, elliptical, or any other suitable configuration which will provide an intersection between the groove and opening which is closer to the socket base and contact assembly than the curved portion of the opening, which allows the spring pressure in the contact assembly to push the pins out into the curvature to lock the bulb.

The contacts 110 and 112 of the socket base and contact assembly 26 are oriented such that when the pins of the bayonet bulb 30 are in their locked position within openings 134 and 136, the bulb contacts will engage the contacts 110 and 112.

The unitary handle and shaft member 20 shown assembled in a complete operating mechanism in FIGS. 1 and 2, is essentially identical to the unitary handle and shaft member shown in FIGS. 3 and 4, except that member 20 has an additional longitudinal groove 150 disposed in its surface 98 which defines the inner diameter of the shaft 24 at its handle end. Groove 150 makes the unitary handle and shaft assembly 20 suitable for use with the conventional socket base and contact assembly 26 shown in FIG. l, or with la new and improved socket base and contact assembly 152," shown in perspective in FIG. 5, and shown in assembled relation with theunitary handle and shaft assembly 20', in FIG. 6.

More specifically, the socket base and contact assembly 152, shown in FIGS. 5 and 6, is constructed to accept a bayonet-type light bulb 154 having a single contact 15'6. The other electrical contact to the light bulb 154 is made through its metallic tubular base portion 158, on which its bayonet pins are mounted, such as pin 160.Y Socket base and contact assembly 152 include an insulating body portion 162 having a substantially cylindrical shape, and which has first and second diameters deining cylindrical surfaces 164 and 166. The diameter defined by surface 1-64 is slightly larger than the diameter defined by surface 166, in order to provide a shoulder which mates with the shoulder between surfaces and 102 of the shaft 24.

The end of the insulating socket base 162 which faces the handle end of the shaft 24 is longitudinally stepped, to provide first and second surfaces 168 and 170 perpendicular to the axis of the shaft 24, with surface 168 being closer to the handle end of the shaft 24 than surface 170. Each of the surfaces 168 and 170 has a groove therein dimensioned to receive and align an electrical contact, with surfaces 168 having a groove for receiving a contact 172, and surface 170 having a grove for receiving a contact 174. Contact 172 is adapted to engage the single contact 156 of the light bulb 154, and contact 174 is adapted to engage the tubular metallic base portion 158 of the light bulb 154. Two contacts are utilized, instead of using the shaft material as the ground return, as the electrical conductivity of the skin of the anodized aluminum shaft is poor, which would provide unreliable operation of the signal light.

Contact 172 is a fiat metallic ribbon formed into a substantially U-shape, with the metal of which it is formed having spring characteristics which cause the contact to return to its original U-shaped dimension after being deformed, and which resist deformation with a predetermined force in order to urge the bulb 154 towards the handle end of the shaft 24, `when the bulb is in its assembled position. Contact 172 may be made of any one of several suitable materials, such as one of the berylliumcopper alloys, or certain of the stainless steels which have the desired spring-like characteristics. Contact 172 has a first leg portion 180, having an opening therein, with the first leg portion fitting into the groove disposed in surface 168, and a second leg portion 182 joined to the first leg portion by the curved portion of the U. The second leg portion 182 engages contact 156 of light bulb 154 with the contact 156 pressing the second leg portion 182 towards the first leg portion when the bulb 154 is in its locked position.

Contact 172 is fixed to base assembly 162 by a contact rivet 186, which also serves as an electrical conductor through the socket base 162. Rivet 186 may be inserted through the opening in contact 172 and pressed through a suitable opening in the socket base 162, to form a sealed assembly, or the rivet and contact may be molded in place when the socket base is formed. The socket base 162 may be formed of any suitable resin system, such as a phenolic.

Contact 174, which may be formed of the same springlike material as contact 172, is substantially L-shaped, having a portion 190 which is placed in the groove disposed in surface 170, which portion has an opening therein for receiving a contact rivet 192, similar to the Contact rivet 186. Contact 174 also has a longitudinally extending portion 194 which extends outwardly from surface 170 towards the handle end of the shaft 24, within the third longitudinal groove 150 provided in surface 98 of shaft 24. Portion 194 of contact 174 has a curved section 196 therein which extends outwardly from the groove 150 for a distance sufficient to contact the metallic base 158 of bulb 154, and to be slightly depressed by the base 158 to assure a good tight electrical contact.

The contact rivets 186 and 192 have a head portion at one end thereof, in order to secure the contacts 172 and 174 in fixed position relative to the socket base 162, and they have blind openings at their other ends for accepting electrical leads 198 and 200, respectively. After the leads 198 and 200 are disposed within these openings, the ends of the rivets are crimped to mechanically fix the leads and to assure good electrical contact.

The socket base and contact assembly 152 has many advantages over the prior art socket base and contact assemblies of similar function. It completely eliminates the spring loaded pins of the prior art, which are not only costly, but which cause excessive resistance to rotation of the light bulb. The single contact of a single contact type bulb, is axially located, and it engages a single U-spring contact which is also axially located. Thus, the bulb 154 may be inserted into its operating position, and removed with relative ease, without deleteriously affecting the locking action of the bulb and shaft. The contact rivets perform the functions of holding the contacts in assembled relation with the socket base, they provide the electrical conductor through the socket base, and they provide the fixed connection to the electrical leads. The longitudinal step in the socket base 162 allows a single contact bulb to be used without the disadvantage of returning the electrical circuit through the shaft.

In summary, there has been disclosed a new and improved operating mechanism which is substantially less costly to manufacture than similar operating mechanisms of the prior art. The number of parts in the assembly have been substantially reduced without loss of function. The construction for accepting a bayonet type light bulb allows the handle and shaft to be die cast as a unitary assembly, eliminating the forged and machined parts of the prior art, which must be subsequently brazed together. Further, the socket base and contact assembly for the signal light has been changed to reduce its complexity and cost, while improving its operation.

Since numerous changes may be made in the above described apparatus and different embodiments of the invention may be made without departing from the spirit thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative, and not in a limiting sense.

We claim as our invention:

1. An operating mechanism adapted to be disposed through an opening in a transformer casing for actuating protective apparatus disposed therein, comprising:

a substantially tubular member adapted to be disposed in fixed, sealed relation through an opening in a transformer casing,

a unitary handle and shaft member, said unitary handle and shaft member including a hollow shaft having first and second ends, and an integral handle disposed at the first end of said hollow shaft, the second end of said hollow shaft being adapted to receive an operating arm connectable to the protective apparatus to be actuated, said unitary handle and shaft disposed through the opening in said tubular member, in sealed rotatable relation therewith,

said hollow shaft having first and second longitudinal grooves in the surface which defines its inside diameter, adapted to lguide the pins of a bayonet-type light bulb, said first and second longitudinal grooves disposed 180 apart and extending inwardly from the first end of said hollow shaft for a predetermined dimension,

said hollow shaft having first and second substantially circular openings disposed transversely through the wall portion thereof, which are disposed apart, and which intersect one side of said first and second longitudinal grooves, respectively, said first and second circular openings adapted to receive the pins of a bayonet-type light bulb, with said first and second circular openings disposed relative to said first and second grooves, respectively, Such that said circular openings are closer to the first end of said hollow shaft than the intersection of said circular openings with said grooves,

and socket base means disposed in sealed relation within the opening of said hollow shaft,

said socket base means including electrical contact means adapted to engage the contacts of a bayonettype light bulb, and to urge the light bulb towards the first end of said hollow shaft means.

2. The operating mechanism of claim 1 wherein said unitary handle and shaft member is constructed of die cast aluminum.

3. The operating mechanism of claim 2 wherein said die cast aluminum is anodized.

4. The operating mechanism of claim 1 wherein said electrical contact means of said socket base means includes two similar spring loaded contacts adapted to engage the contacts of a bayonet type light bulb of the type having two spaced insulated electrical contacts which project outwardly from the base thereof.

5. The operating mechanism of claim 1 wherein said electrical contact means of said socket base means includes a substantially U-shaped first contact member having first and second leg portions, one of which is adapted to engage the contact of a bayonet type light bulb of the type having a single insulated contact projecting outwardly from the base thereof, and a tubular metallic base portion which provides the other connection to the bulb, and a second substantially L-shaped contact member having a portion which extends outwardly from said socket base means towards the first end of said hollow shaft, which is adapted to engage the tubular metallic base portion of the bulb.

6. The operating mechanism of claim 5 wherein said hollow shaft member has a third longitudinal groove disposed in the surface of its inside diameter, with the portion of said second contact member which extends outwardly from said socket base means disposed in said third groove.

7. The operating mechanism of claim 5 wherein said first contact member has its first leg portion fixed to said socket base means, and the second leg portion of said first contact member is adapted to engage the single contact on the bulb, with the bulb moving the second leg portion toward the first leg portion when it nears the axial location of its intended operating position, said first contact member formed of an electrically conductive material which resists the bending thereof with a predetermined force, to continuously urge the light bulb towards the first end of said hollow shaft, and which returns to substantially its original unstressed position following removal of the bulb.

8. The operating mechanism of claim 7 wherein said socket base means is longitudinally stepped to provide first and second surfaces perpendicular to the axis of said hollow shaft which face the first end of said hollow shaft, With said first perpendicular surface being closer to the first end of said hollow shaft than said second perpendicular surface, said first contact member being fixed to said first perpendicular surface, and said second contact member fixed to said second perpendicular surface.

9. The operating mechanism of claim 8 wherein said first and second perpendicular surfaces each have a groove disposed therein of predetermined orientation, said first and second contact members each having a portion disposed in the grooves of said first and second surfaces, respectively.

10. The operating mechanism of claim 9 wherein the portions of said lirst and second contact means disposed in the grooves of said lirst and second perpendicular surfaces have an opening disposed therein, and including rst and second contact rivets each having first and second ends, which extend through said openings in said rst and second contact members, respectively, and longitudinally through said socket base means, the first ends of said first and second contact rivets being larger than said openings to tix said rst and second contact members to said socket base means, the second ends of said first and second contact rivets extending outwardly from said socket base lo means towards the second endxof isaid hollow shaft, said second ends being adapted to receive electrical leads.

References Cited UNITED STATES PATENTS 2,356,055 8/1944 Hodnette et al. 337-79X 2,765,383 10/1956 Cooper et al.

HERMAN O. JONES, Primary Examiner U.S. Cl. X.R. 20G-16S, 172 

